Heretofore, the mixing of sounds has involved the use of sound volume and two-dimensional position information, among others. For example, PTL 1 describes techniques for detecting the positions of microphones and musical instruments arranged on the stage using a mesh-type sensor for example, the results of the position detection serving as a basis for displaying, on a control table screen, objects by which parameter values of the microphones and musical instruments can be changed. This process intuitively associates the objects with the microphones and musical instruments in controlling their parameters.